Heat exchange conduit for oil coolers



Feb. 3, 1953 ,s. PRZYBOROWSKI 2,627,233

HEAT EXCHANGE CONDUIT FOR OIL COOLERS Filed Nov. 2'7, 1950 2 SHEETS-SHEET l 5 T 6 I 3hnentor Sfamslaus Prgyfiorowsh,

Feb. 3, 1 5 s. PRZYBOROWSKI 2,627,283

HEAT EXCHANGE .CONDUITFOR OIL COOLERS Filed NOV. 27, 1950 I 2 SHEETS--SHEET 2 -2 F1228. i, 27 I 4 6 6 6 6 f 4 Zhwentor i tgrneg passages.

Patented Feb. 3, 1 953 U N I T E D S TATES PAT .E N T F P ICE HEAT EXCHANGE CONDUIT FOR OIL 'COOLERS Stanislaus lrzyborowski, Kenmore, N. Y., assignor to Fedders-Quigan Corporation, Buffalo, N. Y., a corporation of New York ApplicationNovember 27, 1950, Serial No. 197,680

paratus for oil in automatic transmissions, al-

though the invention may be appliedto other heat transfer problems, and wherein it is desired to efiect a heat exchange between two confined fluids, or between one confined and one unconfined fluid.

Oil coolers have heretofore been proposed to cool the lubricating oil of internal combustion engines and compressors, and have generally contemplated the withdrawal of the oil from the crankcase for circulation through an external heat interchanger. Another problem relating to oil cooling arises in connection with hydraulic power transmissions, such as are intended for use with automotive power plants, and wherein the heat developed by the circulation or agitation of the hydraulic fluid suiliciently increases its temperature as to require extraneous cooling. Many types or" crankcase oil coolers are unsuited for this service. Transmission oil is of different viscosity, the temperature ranges are not the same, and problems of space and flow resistance make relatively bulky coolers, and-long connecting lines, practically unsatisfactory.

It is well understood that when the oil is cold, and is therefore at a relatively high viscosity, its fiow through a cooleris lowered, and it tends to exert abnormal pressures on the walls of the flow Proposals have heretofore been advanced to icy-pass the main heat exchange pas- -sa'ges of the cooler until the oil becomes warm, with its viscosity correspondingly reduced, so that it may flow through themain passages at lower pressure and with appreciable Velocity. The incorporation of by-pass valves and passageways on a cooler adapted for use with hydraulic transmissions, however, adds greatly to the cost, presents another service problem, and interferes with arranging the cooler satisiactorily in the confined space available iorit.

The presentinvention provides a solution for these difficulties byproviding anoilcoolerorheat invention, which have been found to be highly e'fiicient in service, are illustrated in the accompanying drawing, wherein:

Fig. l is a plan, with portions brokenaway, of one form of oil cooler;

Fig. 2 is a fragmentary view taken substantially along the line 2-2 of Fig. 1, further illustrating the cooler;

Fig. 3 is an enlargediragmentary'sectiontaken on the line 3-3 of Fig. l;

Fig. l is a fragmentary enlarged "plan of the internal oil distributing element of the cooler;

Figs. 5, 6, and '7 are additional views of the distributing element, taken substantially on the'correspondingly numbered lines of Fig. 4;

Fig. 8 is a view similar to Fig. l of another form of the invention, providing a different oil flow path;

Fig. 9 is an enlarged view on the line "99 of Fig. 8, particularly showing a bafile member;

Fig. 10 is a perspective of the baffle member of Figs. 8 and 9; and

Fig. 11 is a section through anotherformof oil cooler.

The oil cooler shown-in Fig. l, and also in Fig. 8, comprises an external maincasing 2i formed of two stamped rectangular pan-like halves 22 and 23. The part is formed with a flange 2 while .the part 23 is formed with a longer flange '25 which is adapted, upon final assembly, to be rolled over the flange 2' 3 to provide alocl; joint. Each part is formed at diagonally opposite corners with similar belied embossments 25 which align. in pairs to form inlet or outlet openings To these may be attached'fittings 23;which in turn may be connected to tubes, not shown, for admitting coolant to the oil cooler. Specifi cally, it is contemplated that thecasing 2! Will be connected to the engine cooling liquidcircuit, so that the casing will be flooded with circulating water or other liquid coolant'when in use,as indicated by'the conventional brokenlight lines'in Fig. 3.

Within the casing 29 are one or more oil'recei'ving and distributing heatexchange conduit's:,generally designated by the reference numeral at. Two are shown in Figs. 2 and 8, but it should be understood that a light duty cooler may require only one conduit,'while'a heavy duty type, or one operating with relatively high temperature coolant, may require several. Each unit comprises a pair of shallow pan-like rectangular plates 3 I and 32, formed with telescoping flanges 33an'd 34 so that, when the plates are superimposed, they form "a confined conduit or; passageway. When more than one unit 30 is tobe employee,

aczmss the plates 3| and 32 are formed at each end with externally projecting cylindrical flanges 35 which align with each other upon assembly, and which nest within the apertures of spacing and supporting collars 36. One plate 3| or 32 is also formed at each end with apertures 31 adapted to be aligned with spacing and supporting collars 38 which fit into openings 39 formed in the casing portion 22.

The collars 38 are drilled and tapped to receive connectors, not shown, by means of which the oil to be cooled may enter the conduits 30 at one end and flow to discharge through the companion collar at the opposite end. In the arrangement shown in Figs. 1 to 3, it will be apparent that the oil flows in parallel paths through the two units 30, the entering oil dividing itself through the aperture formed by the flanged portions 35 and collars 33.

Each conduit 33 is internally provided with a heat transfer and distributing plate 3|, indicated more or less schematically in Fig. l, and shown in detail in Figs. 4 to 7. The plate 4| is formed from sheet metal stock by means of dies which press bumps 32, 43, 44, and other bumps 42a, 43a, and 44a, into the sheet in opposite directions from the original plane of the sheet, which is indicated by the broken line P in Fig. 7. It will be noted that the bumps 42, 43, and 44 are arranged in rows, and that they lie above and below, as viewed in Fig. i, of a median line M drawn through the bumps of each row. Stated otherwise, the bumps 42, 43, 34 form a series of staggered and somewhat sinusoidal spaced rows.

It will also be seen that the bumps 42, 33, 43 are spaced from each other, but are interconnected by other smaller bumps 45, 43, of less elevation than the larger bumps 42, 43, 44. To differentiate between these bumps, the large ones may be termed primary bumps, and the smaller ones designated as secondary bumps. As viewed in Fig. 4, the bumps 42, 43, 44, 45 and 46 appear to be elevated above the plane of the paper. If a specimen made in accordance with the figure is turned over, then the bumps 42a i6a would appear elevated, and the first noted bumps would be depressed. All of the bumps are generally smooth or moundlike, although the primary bumps have appreciable surface area on their tops, as will be apparent from Figs. and 6. The edges of the die pressed sheet are formed with corrugated marginal portions 41 delimited by comparatively straight sides 48 and fiat crests 49, which crests are disposed substantially in the reference median lines M of the several rows of primary bumps.

As shown by the broken lines 3| and 32 in Figs. 5, 6, and 7, the primary bumps 42, 42a, etc. abut the inner faces of the casing 2|. The various rows of bumps, with the walls of the portions 3| and 32, thus define a plurality of channels 5|, 52, of tortuous or sinusoidal configuration, through which the oil may flow. It will also be seen that the secondary or connecting bumps 45, 46, 45a, 45a, do not contact the walls of the casing portions 3| and 32, but are slightly spaced therefrom to provide pressure relief ports 53. Under some operating conditions, the viscosity of the oil may be such as to create localized and vagrant pressure differentials between the channels. Such pressures force some of the oil into adjacent channels, thus rapidly equalizing the pressures throughout the various channels to relieve undue stress and add to the uniformity 9.! heat transfer,

As best shown in Figs. 1 and 3, the distributing plates 4| are cut from the formed stock and disposed transversely of the plates 3| and 32 between the inner margins thereof. They are sufliciently spaced from the inlet and outlet fittings to form an uninterrupted zone 55 at each end of the conduit, providing a distributing or collecting reservoir for the various channels. The oil may therefore flow lengthwise of the conduit 30, in a plurality of generally confined paths, but from which it may escape in part into other channels, as previously explained. The high ratio of internal surface in contact with the oil, to the external surface in contact with the coolant fiowing around the conduits 39, and the substantial amount of direct contact between the crests of the bumps and the walls of the conduit sections 3| and 32, thus assure an efiicient heat transfer. These attributes are, of course, coordinated with the nature of the channels 5|, 52, whose smooth walls reduce friction, and whose sinusoidal form imparts desirable turbulence.

To assemble the cooler, a sheet of brazing metal is laid in the casing section 32 to cover its entire internal area, the plate pieces 4| are laid on the sheet, and are covered by another sheet. The mating casing section 3| is then applied, and the unit is then assembled with the collars 36 and 38. These may be provided with annular grooves, as shown in Fig. 3, to receive rings 51 of brazing material. The subassembly is then oven baked to bond the parts together at their regions of contact. Thereafter, the subassembly of conduits 3B is assembled with the casing sections 22 and 23, the flanges '24 and 25 are coated with brazing metal, and the joint between them is formed. The assembly is then baked, with the collar 38 facing down, so that the ring 57 may flow into the joint made with the aperture 39. A properly assembled and baked unit should withstand test pressures of one hundred pounds per square inch without leakage or deformation, which, considering that fairly thin stock is used, indicates the high measure of strength and ruggedness of the conduit.

The modification shown in Figs. 8, 9, and 10 employs the same external casing 2|, sections 3|, 32, and collars 35 and 38, which therefore need not again be described. The main difference is in the arrangement of the plate 4| within the conduits 30a. It will be seen that these are positioned with their channels disposed transversely, rather than longitudinally, as was explained in connection with Fig. l. The plates 4| are spaced from the ends of the conduit, to provide reservoirs 6| around the inlet and outlet fittings 62 and 33, which are herein shown as external nipples brazed to the outer surface of the casing 2|. The plates are alsospaced from the side walls of the portions 3| and 32, to provide ducts 64 and 65.

Small stop blocks or baffles 36, of channel shaped section, asshown in Fig. 10, are inserted at each end of the duct 55, and midway of the duct 34. These are formed with projecting tabs 3'! on their webs, which enter the space between adjacent marginal sides 48 to retain the plate 4| in proper alignment, and to aid in blocking flow past the baiiies. Assuming arbitrarily that the nipple 63 is the inlet fitting, it will be seen that the bafiie 66 at the lower right of Fig. 8 prevents direct flow into the duct 35. The path of the 7 oil is into duct 64 until it encounters the upper 4| to the duct 65, and then in a reverse direction through the plate 4| to the left hand portion of the duct 64, and thence into the outlet fitting 62. This arrangement increases the total length of the fiow path through the conduit without excessive increase in pressure drop, and thus increases the temperature reduction of the oil between inlet and outlet.

The embodiment shown in Fig. 11 shows how conduits 3th may be connected for straight series flow, as distinguished from parallel fiow presented in Fig. 1. The conduits 3% are interconnected at one end by collars H, and are equipped with like inlet and outlet fittings l2 and 13 at their opposite ends, which have collar portions 14 to abut the walls of external casing sections 15 and E6. The distributing plate 4! is laid in the conduits longitudinally, as described in connection with Fig. 1. The sections 15 and it are, of course, formed with suitable water inlet and outlet openings, which it is deemed unnecessary to illustrate to explain the oil circuit. This arrangement further increases the length of the flow path through the cooler.

It will be obvious that the outer casings could be removed in each of the embodiments, and cooling effected by air or other unconfined fluid, and that external fins could be applied to the various heat exchange conduits, if so desired. It will also be understood that it is intended to afford to the invention a scope commensurate with that encompassed by the following claims.

I claim:

1. A heat transfer conduit comprising fiat spaced wall members forming a confined passageway and a distributing plate interposed between said wall members, said distributing plate being formed with spaced rows of spaced primary bumps which are alternately offset to either side of a median line through said rows, thereby to form tortuous channels between said rows, the height of said bumps being such as to engage the inner surfaces of said wall members, the bumps of each row being interconnected by and merging into each other through secondary 4 bumps of less height than the primary bumps and which are slightly spaced from the inner surfaces of said wall members, thereby providing gaps through which liquid flowing through said channels may distribute itself transversely from one row to another.

2. A heat transfer conduit as set forth in claim 1, wherein the spaced wall members are formed with liquid inlet and outlet openings at opposite ends of the conduit, and the distributing plate is slightly spaced from said openings to provide distributing and collecting reservoirs.

3. A heat transfer conduit comprising substantially rectilinear spaced wall members formed with inlet and outlet openings at opposite ends of the conduit, a distributing plate interposed between the Wall members and spaced from the edges thereof thereby to provide open ducts on opposite sides of the conduit, said plate being formed with rows of alternately offset primary bumps of such height as to contact the wall members, thereby to provide tortuous channels between the rows, said channels being positioned transversely of the conduit to provide a plurality of flow passages between the ducts, and baiiles positioned in the ducts in alternate relation to each other, thereby to cause fluid flowing through the conduit from the inlet to the outlet opening to fiow transversely and in first one direction and then the other.

4. A heat transfer conduit as set forth in claim 3, wherein the baifies are formed as small blocks fitting snugly between the edges of the conduit and the distributing plate, and with projecting tabs partially entering the adjacent channel of the plate.

STANISLAUS PRZYBOROWSKI.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 785,580 Shiels et a1. Mar. 21, 1905 1,987,604 Corbett Jan. 15', 1935 2,131,929 Amme Oct. 4., 1938 2,281,754 Dalzell May 5, 1942 

